Method and system for segmental flow control in oil-gas well

ABSTRACT

A method and a system for segmental flow control in an oil-gas well are disclosed. The oil-gas well includes a first annular space ( 111 ) and a second annular space ( 103 ). The first annular space ( 111 ) is formed with the space between the borehole wall ( 101 ) of the oil-gas well and a perforated tube ( 102 ) which is in the oil-gas well and extends along an axial direction of the oil-gas well; The second annular space( 103 ) which is formed with the space between the perforated tube( 102 ) and a flow-control filter string ( 105 ) which is in the perforated tube( 102 ) and extends along the axial direction of the oil-gas well. The method includes filling anti-channeling isolating particles ( 109 ) in the first annular space ( 111 ) and the second annular space ( 103 ) to enable fluid to flow in the first annular space ( 111 ) and the second annular space ( 103 ) filled with the anti-channeling isolating particles ( 109 ) in the manner of seepage.

FIELD OF THE INVENTION

The present application relates to a flow control method in an oil-gaswell exploitation field, and in particular to a sectional flow controlmethod using a flow control filter string in an oil-gas well having aperforated pipe.

BACKGROUND OF THE INVENTION

An oil-gas well generally refers to a production well in the oil-gasfield development in a broad sense, including an oil well, a gas well,an injection well and so on. In the production process of the oil-gaswell, due to the heterogeneous characteristic of the oil reservoir, theoil-gas well, regardless of a vertical well or a horizontal well, has tobe sealed off and separated into multiple independent zones forproduction. The oil-gas well production mentioned herein includes theproduction and injection of the fluid in the oil-gas well productionprocess, for example, injecting water and vapor into the formation inthe petroleum exploitation or production process, and injecting chemicalagents for improving the oil field recovery ratio, and also includes theinjection of acid liquor into the formation in some operation processes,etc.

During the process of sealing off and separating the oil-gas well intomultiple independent zones for production, a device for controlling flowrate in sections (for example, a flow control filter string), and adevice for separating the production section of the oil-gas well intoseveral flow units along the axial direction of the oil-gas well (forexample, a packer) are generally used to realize the seal and separationof the zones, so as to realize relatively independent production.

FIG. 1 is a schematic view illustrating the flow control by using a flowcontrol filter string and a packer in an open hole. In FIG. 1, referencenumeral 1 indicates a borehole wall of the oil-gas well, referencenumeral 2 indicates a flow control filter string, reference numeral 3indicates an annular space between the flow control filter string andthe borehole wall, reference numeral 4 indicates a packer hung with theflow control filter string, and reference numeral 5 indicates a flowcontrol packer.

The process of sectional flow control is briefly described hereinafterwith reference to FIG. 1. FIG. 1 shows a non-oil-bearing formation, anoil-bearing formation and bottom water under the oil-bearing formation.Various formations are schematically indicated by horizontal lines inFIG. 1, though the person skilled in the art may understand that theseformations may not be horizontal, which depends on the geologicstructure of the locality where the oil-gas well is located. The oil-gaswell as shown in the figure includes a vertical section and a horizontalsection. The horizontal section substantially extends along theoil-bearing formation so as to increase the contact area between theborehole wall and the oil-bearing formation. FIG. 1 illustratively showstwo zones having different permeability, i.e. a high permeability zoneand a low permeability zone. Under the situation without flow control inthe oil-gas well (i.e. no packer 5 is provided in FIG. 1), since thepermeability of the two zones is different, a flow rate of the fluid inthe high permeability zone is larger than a flow rate of the fluid inthe low permeability zone. In this case, due to the difference betweenthe pressure of the bottom water and the pressure inside the oil-gaswell, the bottom water under the oil-bearing formation may firstly passthrough the high permeability zone and enter into the oil-gas well,which may cause the decrease of oil and gas and the increase of water inthe production of the oil-gas well. This should be avoided in theproduction.

Currently, as shown in FIG. 1, the sectional flow-rate controlproduction in many oil-gas wells is realized as follows. A flow controlfilter string 2 is lowered into the production section inside theoil-gas well, and the flow control filter string 2 and the packer 5 areused to effectively seal off and partition an annular space between theflow control filter string 2 and the production section inside theoil-gas well, i.e. axial channeling passage of fluid outside the flowcontrol filter string is blocked, thereby realizing a better sectionalflow-rate control production. Generally, the packer is provided betweentwo zones having different permeability. Since the flow control filtercan play a role of flow-rate control, the packer is used to pack off thezones having different permeability so as to perform independent controlor sectional control of various zones having different permeability.Therefore, it is possible for the oil-gas well to achieve a goodproduction, and to effectively control the quantity of the bottom waterentering into the oil-gas well.

However, the current well completion of the oil-gas well is achieved byrunning a perforated pipe into an open hole, and an annular spacebetween the perforated pipe and the open hole wall is not sealed byfilling cement or other materials between the perforated pipe and theborehole wall. The well completion method has an advantage of the lowcost, and a disadvantage that the annular space becomes a passage forfluid channeling, so that it is difficult to realize the sectional flowcontrol in the later production. Each meter of the perforated pipe isprovided with several to dozens of holes with a diameter about 10 mm.The perforated pipe is mainly used in the oil-gas well to support theborehole wall and prevent lumps in the well from entering into theperforated pipe so as to ensure that the whole flow passage of theoil-gas well is not blocked by lumps.

As shown in FIG. 2, if the flow control technology using the packer inthe open hole as shown in FIG. 1 is directly applied in the existingoil-gas well having the perforated pipe, the annular space between theperforated pipe and the borehole wall cannot be packed off Thus, thebottom water entering into the oil-gas well may flow axially in theannular space between the perforated pipe and the borehole wall. Thus,the annular space between the perforated pipe and the borehole wallforms an axial channeling passage, which destroys the pack-off effectbetween the flow control filter string in the perforated pipe and theperforated pipe, and cannot control the amount of water satisfactorily.In FIG. 2, reference numeral 11 indicates a borehole wall of the oil-gaswell, reference numeral 12 indicates a perforated pipe, referencenumeral 13 indicates an annular space between the perforated pipe andthe borehole wall, reference numeral 14 indicates a packer hung with theperforated pipe, reference numeral 15 indicates a flow control filterstring, reference numeral 16 indicates a flow control filter on the flowcontrol filter string, reference numeral 17 indicates a packer providedin the annular space between the flow control filter string and theperforated pipe, and reference numeral 18 indicates a packer hung withthe flow control filter string. A direction of arrows in the figureindicates the fluid channeling direction. As shown in FIG. 2, the fluidin the formation passes through the borehole wall and enters into theannular space between the borehole wall and the perforated pipe, so thatthe axial channeling is formed in the annular space between the boreholewall and the perforated pipe, and then passes through the flow controlfilter and enters into the flow control filter string. This axialchanneling destroys the pack-off effect of the packer provided betweenthe flow control filter string and the perforated pipe, thus a goodwater control effect can not be realized.

SUMMARY OF THE INVENTION

A technical problem to be solved by the present application is toprovide a sectional flow control method using a flow control filterstring in an oil-gas well having a perforated pipe, in which the annularspace between the flow control filter string and the perforated pipe andthe annular space between the perforated pipe and the borehole wall arefilled with anti-channeling pack-off particles, so as to realize a goodpack-off effect, thereby realizing a good sectional flow controlproduction.

For solving the above problem, one embodiment of the present applicationprovides a sectional flow control method in an oil-gas well, wherein theoil-gas well includes a first annular space formed between a boreholewall of the oil-gas well and a perforated pipe, and a second annularspace formed between the perforated pipe and a flow control filterstring. The perforated pipe is located inside the oil-gas well andextends along an axial direction of the oil-gas well. The flow controlfilter string is located inside the perforated pipe and extends alongthe axial direction of the oil-gas well. The method includes the stepof: filling anti-channeling pack-off particles into the first annularspace and the second annular space such that fluid can flow in apenetration manner in the first annular space and the second annularspace filled with the anti-channeling pack-off particles.

Preferably, filling the anti-channeling pack-off particles into thefirst annular space and the second annular space is performed byinjecting particle-carrying fluid with the anti-channeling pack-offparticles into the first annular space and the second annular space.

Preferably, the particle-carrying fluid has a density substantiallyequal to a density of the anti-channeling pack-off particles.

Preferably, the particle-carrying fluid is water or aqueous solution.

Preferably, the anti-channeling pack-off particles are high molecularpolymer particles with an average particle size ranging from 0.05 mm to1.0 mm and a density ranging from 0.8 g/cm³ to 1.4 g/cm³.

Preferably, the anti-channeling pack-off particles are high molecularpolymer particles with an average particle size ranging from 0.1 mm to0.5 mm and a density ranging from 0.94 g/cm³ to 1.06 g/cm³.

Preferably, the anti-channeling pack-off particles are high-densitypolyethylene particles with an average particle size ranging from 0.1 mmto 0.5 mm and a density ranging from 0.90 g/cm³ to 0.98 g/cm³.

Preferably, the anti-channeling pack-off particles are styrene anddivinylbenzene crosslinking copolymer particles with an average particlesize ranging from 0.05 mm to 1.0 mm and a density ranging from 0.96g/cm³ to 1.06 g/cm³.

Preferably, the anti-channeling pack-off particles are polypropylene andpolyvinyl chloride high molecular polymer particles with an averageparticle size ranging from 0.05 mm to 1.0 mm and a density ranging from0.8 g/cm³ to 1.2 g/cm³.

Preferably, the anti-channeling pack-off particles are filled into thefirst annular space and the second annular space until the first annularspace and the second annular space are substantially full of theanti-channeling pack-off particles, and the first annular space and thesecond annular space are closed. Preferably, the oil-gas well is ahorizontal well or an inclined well.

Preferably, a difference between a density of the particle-carryingfluid and a density of the anti-channeling pack-off particles is withina range of ±0.4 g/cm³ or a range of ±0.2 g/cm³.

According to another embodiment of the present application, a sectionalflow control system for an oil-gas well is provided, including: a firstannular space formed between a borehole wall of the oil-gas well and aperforated pipe; a second annular space formed between the perforatedpipe and a flow control filter string; and anti-channeling pack-offparticles. The perforated pipe is located inside the oil-gas well andextends along an axial direction of the oil-gas well. The flow controlfilter string is located inside the perforated pipe and extends alongthe axial direction of the oil-gas well. The anti-channeling pack-offparticles are filled in the first annular space and the second annularspace such that fluid can flow in a penetration manner in the firstannular space and the second annular space filled with theanti-channeling pack-off particles.

Preferably, the first annular space and the second annular space arefilled by injecting particle-carrying fluid with the anti-channelingpack-off particles into the first annular space and the second annularspace.

Preferably, the particle-carrying fluid has a density substantiallyequal to a density of the anti-channeling pack-off particles.

Preferably, the particle-carrying fluid is water or aqueous solution.

Preferably, the anti-channeling pack-off particles are high molecularpolymer particles with an average particle size ranging from 0.05 mm to1.0 mm and a density ranging from 0.8 g/cm³ to 1.4 g/cm³.

Preferably, the anti-channeling pack-off particles are high molecularpolymer particles with an average particle size ranging from 0.1 mm to0.5 mm and a density ranging from 0.94 g/cm³ to 1.06 g/cm³.

Preferably, the anti-channeling pack-off particles are high-densitypolyethylene particles with an average particle size ranging from 0.1 mmto 0.5 mm and a density ranging from 0.90 g/cm³ to 0.98 g/cm³.

Preferably, the anti-channeling pack-off particles are styrene anddivinylbenzene crosslinking copolymer particles with an average particlesize ranging from 0.05 mm to 1.0 mm and a density ranging from 0.96g/cm³ to 1.06 g/cm³.

Preferably, the anti-channeling pack-off particles are polypropylene andpolyvinyl chloride high molecular polymer particles with an averageparticle size ranging from 0.05 mm to 1.0 mm and a density ranging from0.8 g/cm³ to 1.2 g/cm³.

Preferably, the first annular space and the second annular space aresubstantially full of the anti-channeling pack-off particles, and areclosed.

Preferably, the oil-gas well is a horizontal well or an inclined well.

Preferably, a difference between the density of the particle-carryingfluid and the density of the anti-channeling pack-off particles iswithin a range of ±0.4 g/cm³ or a range of 0.2 g/cm³.

According to another embodiment of the present application, a sectionalflow control method using a flow control filter string in an oil-gaswell having a perforated pipe is provided, wherein the oil-gas wellhaving the perforated pipe includes a borehole wall of the oil-gas welland the perforated pipe running in the oil-gas well, one end of theperforated pipe adjacent to a wellhead is fixedly connected to theborehole wall, and an annular space is formed between the perforatedpipe and the borehole wall.

The sectional flow control method using a flow control filter stringincludes the following steps:

1) running the flow control filter string into the perforated pipe via arunning string, wherein the flow control filter string is provided witha flow control filter, one end of the flow control filter stringadjacent to the wellhead is fixedly connected to the borehole wall, andan annular space is formed between the flow control filter string andthe perforated pipe;

2) injecting particle-carrying fluid with the anti-channeling pack-offparticles into the annular space between the flow control filter stringand the perforated pipe, wherein the particle-carrying fluid carryingthe anti-channeling pack-off particles passes through holes in theperforated pipe and into the annular space between the perforated pipeand the borehole wall, the anti-channeling pack-off particles areaccumulated both in the annular space between the flow control filterstring and the perforated pipe and in the annular space between theperforated pipe and the borehole wall, so that the annular space betweenthe flow control filter string and the perforated pipe and the annularspace between the perforated pipe and the borehole wall are filled withand full of the anti-channeling pack-off particles, a part of theparticle-carrying fluid enters into the flow control filter and thenflows back to the ground, and another part of the particle-carryingfluid passes through the borehole wall and penetrates into theformation;

3) closing the annular space full of the anti-channeling pack-offparticles between the flow control filter string and the perforatedpipe; and

4) disengaging the running string which is connected to the flow controlfilter string, and forming a well completion structure in which theannular space between the flow control filter string and the perforatedpipe and the annular space between the perforated pipe and the boreholewall are filled with the anti-channeling pack-off particles.

The particle density mentioned in the present application is the truedensity of the individual particles, rather than the packing density ofthe particles.

The present application uses water or aqueous solution with a densityabout 1 g/cm³ as the particle-carrying fluid to carry anti-channelingpack-off particles, and the present application uses anti-channelingpack-off particles having almost the same density as theparticle-carrying fluid, thus the particle-carrying fluid may easilycarry the anti-channeling pack-off particles to fill in the annularspace between the flow control filter string and the perforated pipe andthe annular space between the perforated pipe and the borehole wall. Theanti-channeling pack-off particles are accumulated both in the annularspace between the flow control filter string and the perforated pipe andin the annular space between the perforated pipe and the borehole wall,so that the annular space between the flow control filter string and theperforated pipe and the annular space between the perforated pipe andthe borehole wall are filled with and full of the anti-channelingpack-off particles. A part of the particle-carrying fluid enters intothe flow control filter and then flows back to the ground, and anotherpart of the particle-carrying fluid passes through the borehole wall andpenetrates into the formation. Finally, a well completion structure isformed, in which the annular space between the flow control filterstring and the perforated pipe and the annular space between theperforated pipe and the borehole wall are filled with theanti-channeling pack-off particles. The anti-channeling pack-offparticles are filled tightly and there is almost no channeling. Theoil-gas well may effectively be sealed off and separated into multipleindependent zones with combination of the flow control filter string, soas to perform oil-gas well production, realize the object of flowcontrol, and facilitate the flow-rate sectional management, therebybringing good effects of the oil-gas well production, for example,improving the production efficiency of the oil-gas well.

Furthermore, even there still has channeling after filling with theanti-channeling pack-off particles, in production axial channeling ofsmall flow rate of fluid may bring the anti-channeling pack-offparticles to move and to be accumulated towards the channeling directionand then to fully fill the channeling passage, thereby achieving a verygood anti-channeling pack-off effect and realizing the object ofsectional flow control using a flow control filter string in an oil-gaswell with the combination of a flow control filter string.

The formation fluid flows in media formed by the accumulation of theanti-channeling pack-off particles in the penetration manner. Accordingto the principle of the penetration fluid mechanics, the penetrationresistance is proportional to the penetration distance, and is inverselyproportional to the penetration area. The accumulation body of theanti-channeling pack-off particles has a thin thickness, a small sectionand a long axial length. Accordingly, a channeling resistance of theformation fluid flowing in the anti-channeling pack-off particles alongthe axial direction of the oil-gas well is very high. However, when theformation fluid flows along the radial direction of the oil-gas well,the penetration area is big and the penetration distance is short, thusthe flow resistance is very small. The resistance flowing in theaccumulation body for several meters or tens of meters along the axialdirection of the oil-gas well is hundreds times even thousands timesmore than the resistance flowing in the accumulation body for severalcentimeters along the radial direction of the oil-gas well. Due to thegreat difference between the resistance flowing in the accumulation bodyalong the axial direction of the oil-gas well and the resistance flowingin the accumulation body along the radial direction of the oil-gas well,the flow rate flowing in the accumulation body along the axial directionof the oil-gas well is far less than the flow rate flowing in theaccumulation body along the radial direction of the oil-gas well underthe same pressure difference. Thus, under the difference between theresistance flowing in the accumulation body of the anti-channelingpack-off particles along the axial direction of the well and theresistance flowing in the accumulation body along the radial directionof the well, the smooth flow of the formation fluid in the accumulationbody along the radial direction of the oil-gas well may be ensured, andthe flow of the formation fluid along the axial direction of the oil-gaswell may be limited, thereby functioning as a packer.

The present application provides a convenient and useful sectional flowcontrol method using a flow control filter string in an oil-gas wellhaving a perforated pipe, which may pack off the annular space betweenthe flow control filter string and the perforated pipe and the annularspace between the perforated pipe and the borehole wall, thereby havinga good pack-off effect, realizing the sectional flow control productionwell, and satisfying the actual production requirements of the oilfield, for example, improving the oil recovery ratio.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating the flow control by using a flowcontrol filter string and a packer in an open hole in the prior art;

FIG. 2 is a schematic view of a hypothetical state where the flowcontrol technology using the flow control filter string and the packeras shown in FIG. 1 is applied to an oil-gas well having a perforatedpipe, the flow control filter string is lowered into the perforatedpipe, an annular space between the flow control filter string and theperforated pipe is packed off, while an annular space between theperforated pipe and a borehole wall is not packed off;

FIG. 3 is a schematic view of a sectional flow control method using aflow control filter string in an oil-gas well having a perforated pipeaccording to an embodiment of the present application; and

FIG. 4 is a schematic view of a well completion structure according toan embodiment of the present application, in which an annular spacebetween the flow control filter string and the perforated pipe and anannular space between the perforated pipe and a borehole wall are bothfilled with anti-channeling pack-off particles.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Overall, the present application provides a sectional flow controlmethod using a flow control filter string in an oil-gas well having aperforated pipe. The oil-gas well having the perforated pipe thereinincludes a borehole wall of the oil-gas well and the perforated piperunning into the oil-gas well. One end of the perforated pipe adjacentto a wellhead is fixedly connected to the borehole wall, and an annularspace is formed between the perforated pipe and the borehole wall.

The sectional flow control method using the flow control filter stringincludes the following steps:

1) running the flow control filter string into the perforated pipe via arunning string, wherein the flow control filter string is provided witha flow control filter, one end of the flow control filter stringadjacent to a wellhead is fixedly connected to the borehole wall, and anannular space is formed between the flow control filter string and theperforated pipe;

2) injecting a particle-carrying fluid into the annular space betweenthe flow control filter string and the perforated pipe; wherein theparticle-carrying fluid carries the anti-channeling pack-off particles,the particle-carrying fluid carrying the anti-channeling pack-offparticles passes through holes in the perforated pipe and enters into anannular space between the perforated pipe and the borehole wall, theanti-channeling pack-off particles are accumulated both in the annularspace between the flow control filter string and the perforated pipe andthe annular space between the perforated pipe and the borehole wall, sothat the annular space between the flow control filter string and theperforated pipe as well as the annular space between the perforated pipeand the borehole wall is filled with and full of the anti-channelingpack-off particles, a part of the particle-carrying fluid enters intothe flow control filter and then flows back to the ground, and anotherpart of the particle-carrying fluid passes through the borehole wall andpenetrates into the formation;

3) closing the annular space full of the anti-channeling pack-offparticles between the flow control filter string and the perforatedpipe; and

4) disengaging the running string which is connected to the flow controlfilter string, and forming a well completion structure in which theannular space between the flow control filter string and the perforatedpipe and the annular space between the perforated pipe and the boreholewall are filled with the anti-channeling pack-off particles.

The particle-carrying fluid carrying the anti-channeling pack-offparticles is water or aqueous solution.

The anti-channeling pack-off particles may be high molecular polymerparticles with a particle size ranging from 0.05 mm to 0.7 mm and adensity ranging from 0.8 g/cm³ to 1.2 g/cm³.

The anti-channeling pack-off particles may be high molecular polymerparticles with an average particle size ranging from 0.05 mm to 1.0 mmand a density ranging from 0.8 g/cm³ to 1.4 g/cm³.

The anti-channeling pack-off particles may be high molecular polymerparticles with an average particle size ranging from 0.1 mm to 0.5 mmand a density ranging from 0.94 g/cm³ to 1.06 g/cm³.

The anti-channeling pack-off particles may be high-density polyethyleneparticles with an average particle size ranging from 0.1 mm to 0.5 mmand a density ranging from 0.90 g/cm³ to 0.98 g/cm³.

The anti-channeling pack-off particles may be styrene and divinylbenzenecrosslinking copolymer particles with an average particle size rangingfrom 0.05 mm to 1.0 mm and a density ranging from 0.96 g/cm³ to 1.06g/cm³.

The anti-channeling pack-off particles may be polypropylene andpolyvinyl chloride high molecular polymer particles with an averageparticle size ranging from 0.05 mm to 1.0 mm and a density ranging from0.8 g/cm³ to 1.2 g/cm³.

The embodiments of the present application will be described in detailwith reference to the drawings hereinafter.

First Embodiment

The embodiment of the present application provides a sectional flowcontrol method using a flow control filter string in an oil-gas wellhaving a perforated pipe. As shown in FIG. 3, the oil-gas well structurehaving the perforated pipe includes a borehole wall 101 of the oil-gaswell and a perforated pipe 102 running in the oil-gas well. Each meterof the perforated pipe 102 is provided with multiple small holes. Forexample, the number of the small holes is 30. The diameter of the smallholes is configured to be able to prevent lumps from entering into theperforated pipe 102, for example 10 mm. A packer 104 hung with theperforated pipe 102 is provided between an upper portion of theperforated pipe 102 and the borehole wall 101. An annular space 103 isformed between the perforated pipe 102 and the borehole wall 101.

The water control pack-off method according to the embodiment of thepresent application is described in detail with reference to FIG. 3hereinafter, which includes the following steps.

A flow control filter string 105 is run into the perforated pipe 102 viaa running string (not shown). A flow control filter 106 is provided onthe flow control filter string 105. A packer 108 hung with the flowcontrol filter string 105 is provided between an upper portion of theflow control filter string 105 and the borehole wall 101. An annularspace 103 is formed between the flow control filter string 105 and theperforated pipe 102.

A particle-carrying fluid 110 carrying the anti-channeling pack-offparticles is injected into the annular space 103 between the flowcontrol filter string 105 and the perforated pipe 102. Theparticle-carrying fluid 110 carrying the anti-channeling pack-offparticles passes through small holes in the perforated pipe 102 andenters into the annular space 111 between the perforated pipe 102 andthe borehole wall 101. The anti-channeling pack-off particles areaccumulated both in the annular space 103 between the flow controlfilter string 105 and the perforated pipe 102 and in the annular space111 between the perforated pipe 102 and the borehole wall 101, so thatthe annular space 103 between the flow control filter string 105 and theperforated pipe 102 and the annular space 111 between the perforatedpipe 102 and the borehole wall 101 are filled with and full of theanti-channeling pack-off particles. A part of the particle-carryingfluid penetrates through the flow control filter 106 and enters into theflow control filter string 105 and then flows back to the ground, andanother part of the particle-carrying fluid passes through the boreholewall 101 and penetrates into the formation. The direction of arrows inFIG. 3 is the flowing direction of the particle-carrying fluid. Theanti-channeling pack-off particles are high-density polyethyleneparticles with an average particle size ranging from 0.1 mm to 0.5 mmand a density ranging from 0.90 g/cm³ to 0.98 g/cm³. Theparticle-carrying fluid is water.

The packer 108 hung with the flow control filter string 105 is set so asto close both the annular space 103 between the flow control filterstring 105 and the perforated pipe 102 and the annular space 111 betweenthe perforated pipe 102 and the borehole wall 101 which are filled withthe anti-channeling pack-off particles.

The running string (not shown) connected to the flow control filterstring 105 is disengaged and a well completion structure is formed. Inthe well completion structure, the annular space 103 between the flowcontrol filter string 105 and the perforated pipe 102 and the annularspace 111 between the perforated pipe 102 and the borehole wall 101 arefilled with the anti-channeling pack-off particles, as shown in FIG. 4.In FIG. 4, reference numeral 101 indicates the borehole wall of theoil-gas well, reference numeral 102 indicates the perforated pipe,reference numeral 104 indicates the packer hung with the perforatedpipe, reference numeral 105 indicates the flow control filter string,reference numeral 106 indicates the flow control filter on the flowcontrol filter string, reference numeral 107 indicates theanti-channeling pack-off particles filled the annular space between theflow control filter string and the perforated pipe, reference numeral108 indicates the packer hung with the flow control filter string, andreference numeral 109 indicates the anti-channeling pack-off particlesfilled the annular space between the perforated pipe and the boreholewall.

Second Embodiment

In the embodiment of the present application, the anti-channelingpack-off particles are polypropylene and polyvinyl chloride highmolecular polymer particles with an average particle size ranging from0.1 mm to 0.5 mm and a density being 0.97 g/cm³.

The other steps of the method are the same as the first embodiment.

Third Embodiment

In the embodiment of the present application, the anti-channelingpack-off particles are styrene and divinylbenzene crosslinking copolymerparticles with an average particle size ranging from 0.05 mm to 1.0 mmand a density ranging from 0.96 g/cm³ to 1.06 g/cm³.

The other steps of the method are the same as the first embodiment.

In the first, second and third embodiments of the present application,water is used to carry the anti-channeling pack-off particles. Thedensity of water is 1 g/cm³. The density of the anti-channeling pack-offparticles selected in the present application is almost the same as thedensity of water. Therefore, the water may easily carry theanti-channeling pack-off particles to fill in the annular space 103between the flow control filter string 105 and the perforated pipe 102and the annular space 111 between the perforated pipe 102 and theborehole wall 101. The anti-channeling pack-off particles areaccumulated both in the annular space 103 between the flow controlfilter string 105 and the perforated pipe 102 and in the annular space111 between the perforated pipe 102 and the borehole wall 101, so thatthe annular space 103 between the flow control filter string 105 and theperforated pipe 102 and the annular space 111 between the perforatedpipe 102 and the borehole wall 101 are filled with and full of theanti-channeling pack-off particles. A part of the water passes throughthe flow control filter 106 and enters into the flow control filterstring 105 and then flows back to the ground, and another part of thewater passes through the borehole wall 101 and penetrates into theformation. Finally, a well completion structure is formed, in which theannular space 103 between the flow control filter string 105 and theperforated pipe 102 and the annular space 111 between the perforatedpipe 102 and the borehole wall 101 are filled with the anti-channelingpack-off particles.

The formation fluid flows in media formed by the accumulation of theanti-channeling pack-off particles in a penetration manner. According tothe principle of the penetration fluid mechanics, the penetrationresistance is proportional to the penetration distance, and is inverselyproportional to the penetration area. The accumulation body of theanti-channeling pack-off particles is a medium having a thin thickness,a small section and a long axial length, thus the channeling resistanceof the formation fluid flowing in the accumulation body of theanti-channeling pack-off particles along the axial direction of theoil-gas well is very high. However, when the formation fluid flows alongthe radial direction of the oil-gas well, the penetration area is bigand the penetration distance is short, thus the flow resistance is verysmall. The resistance flowing in the accumulation body for severalmeters or tens of meters along the axial direction of the oil-gas wellis hundreds times even thousands times more than the resistance flowingin the accumulation body for several centimeters along the radialdirection of the oil-gas well. Due to the great difference between theresistance flowing in the accumulation body along the axial direction ofthe oil-gas well and the resistance flowing in the accumulation bodyalong the radial direction of the oil-gas well, the flow rate flowing inthe accumulation body along the axial direction of the oil-gas well isfar less than the flow rate flowing in the accumulation body along theradial direction of the oil-gas well under the same pressure difference.Under the difference between the resistance flowing in the accumulationbody of the anti-channeling pack-off particles along the axial directionof the well and the resistance flowing in the accumulation body alongthe radial direction of the well, the smooth flow of the formation fluidin the accumulation body along the radial direction of the oil-gas wellmay be ensured, and the flow of the formation fluid along the axialdirection of the oil-gas well may be limited, thereby functioning as apacker.

The present application provides a convenient and useful sectional flowcontrol method in an oil-gas well having a perforated pipe, which maypack off both the annular space between the flow control filter stringand the perforated pipe and the annular space between the perforatedpipe and the borehole wall. The sectional flow control production may berealized due to the good pack-off effect, so as to improve the oilrecovery ratio and satisfy the actual production requirements of the oilfield.

The production section referred in the present application is ageneralized production section. There may be some non-flowing sections(for example, an interlayer, a sandwich layer and an imperforatedinterval after the casing cementing) along the length of the productionsection.

The flow control filter string in the present application includesfiltering sections and blank sections which are arranged alternately.The blank section is a pipe without holes on its wall surface. Theanti-channeling pack-off particle ring outside the blank sections playsa major role in preventing the axial channeling. The blank sections areprovided in two ways. On the one hand, each filter itself includes afiltering section and blank sections provided at two ends of the filterand provided with screw threads, so that two filters may be connectedvia the screw threads on the blank sections of the two filters. Whenscrewing and connecting the filters above the well, the blank section isa place for setting the pliers. On the other hand, an additional blanksection may be connected between two filters. Under the situation that arelatively long flow control filter string is desired, the flow controlfilter string may be formed by connecting multiple flow control filtersin series.

The anti-channeling pack-off particles in the present application ispreferably circular.

In the embodiments of the present application, a sectional flow controlmethod using a flow control filter string in an oil-gas well having aperforated pipe is provided, wherein the oil-gas well having theperforated pipe includes a borehole wall of the oil-gas well and theperforated pipe running into the oil-gas well, one end of the perforatedpipe adjacent to a wellhead is fixedly connected to the borehole wall,and an annular space is formed between the perforated pipe and theborehole wall.

The sectional flow control method using a flow control filter string ischaracterized by including the following steps:

1) running the flow control filter string into the perforated pipe via arunning string, the flow control filter string being provided with aflow control filter, the flow control filter string being fixedconnected to the borehole wall, and an annular space being formedbetween the flow control filter string and the perforated pipe;

2) injecting particle-carrying fluid, which carries the anti-channelingpack-off particles, into the annular space between the flow controlfilter string and the perforated pipe; wherein the particle-carryingfluid carrying the anti-channeling pack-off particles passes throughholes in the perforated pipe and enters into an annular space betweenthe perforated pipe and the borehole wall, the anti-channeling pack-offparticles are accumulated both in the annular space between the flowcontrol filter string and the perforated pipe and in the annular spacebetween the perforated pipe and the borehole wall, so that the annularspace between the flow control filter string and the perforated pipe andthe annular space between the perforated pipe and the borehole wall arefilled with and full of the anti-channeling pack-off particles;

3) closing the annular space full of the anti-channeling pack-offparticles between the flow control filter string and the perforatedpipe, and closing the pack-off medium in the annular space between theperforated pipe and the borehole wall;

4) disengaging the running string which is connected to the flow controlfilter string; and forming a well completion structure in which theannular space between the flow control filter string and the perforatedpipe and the annular space between the perforated pipe and the boreholewall are filled with the anti-channeling pack-off particles.

The particle-carrying fluid carrying the anti-channeling pack-offparticles is water or aqueous solution.

The anti-channeling pack-off particles may be high molecular polymerparticles with an average particle size ranging from 0.05 mm to 1.0 mmand a density ranging from 0.8 g/cm³ to 1.4 g/cm³.

The anti-channeling pack-off particles may be high molecular polymerparticles with an average particle size ranging from 0.1 mm to 0.5 mmand a density ranging from 0.94 g/cm³ to 1.06 g/cm³.

The anti-channeling pack-off particles may be high-density polyethyleneparticles with an average particle size ranging from 0.1 mm to 0.5 mmand a density ranging from 0.90 g/cm³ to 0.98 g/cm³.

The anti-channeling pack-off particles may be styrene and divinylbenzenecrosslinking copolymer particles with an average particle size rangingfrom 0.05 mm to 1.0 mm and a density ranging from 0.96 g/cm³ to 1.06g/cm³.

The anti-channeling pack-off particles may be polypropylene andpolyvinyl chloride high molecular polymer particles with an averageparticle size ranging from 0.05 mm to 1.0 mm and a density ranging from0.8 g/cm³ to 1.2 g/cm³.

Although the present application has been described with reference tothe preferred embodiments of the present application, it should beunderstood that, the present application is not limited to the disclosedembodiments or structures. On the contrary, it is intended that thepresent application covers various modifications and equivalentsolutions. In addition, various elements of the present applicationdisclosed herein are shown in various exemplary combinations andstructures, but other combinations and structures including more or lesselements or only one element are also deemed to fall into the protectionscope of the present application.

1. A sectional flow control method for an oil-gas well, wherein theoil-gas well comprises: a first annular space formed between a boreholewall of the oil-gas well and a perforated pipe, wherein the perforatedpipe is located inside the oil-gas well and extends along an axialdirection of the oil-gas well; a second annular space formed between theperforated pipe and a flow control filter string, wherein the flowcontrol filter string is located inside the perforated pipe and extendsalong the axial direction of the oil-gas well; and wherein the methodcomprises the step of: filling anti-channeling pack-off particles intothe first annular space and the second annular space such that fluid iscapable of flowing in a penetration manner in the first annular spaceand the second annular space filled with the anti-channeling pack-offparticles.
 2. The method according to claim 1, wherein filling theanti-channeling pack-off particles into the first annular space and thesecond annular space is performed by injecting particle-carrying fluidwith the anti-channeling pack-off particles into the first annular spaceand the second annular space.
 3. The method according to claim 2,wherein the particle-carrying fluid has a density substantially equal toa density of the anti-channeling pack-off particles.
 4. The methodaccording to claim 2, wherein the particle-carrying fluid is water oraqueous solution.
 5. The method according to claim 1, wherein theanti-channeling pack-off particles are high molecular polymer particleswith an average particle size ranging from 0.05 mm to 1.0 mm and adensity ranging from 0.8 cm3 to 1.4 g/cm3.
 6. The method according toclaim 1, wherein the anti-channeling pack-off particles are highmolecular polymer particles with an average particle size ranging from0.1 mm to 0.5 mm and a density ranging from 0.94 g/cm3 to 1.06 g/cm3. 7.The method according to claim 1, wherein the anti-channeling pack-offparticles are high-density polyethylene particles with an averageparticle size ranging from 0.1 mm to 0.5 mm and a density ranging from0.90 g/cm3 to 0.98 g/cm3.
 8. The method according to claim 1, whereinthe anti-channeling pack-off particles are styrene and divinylbenzenecrosslinking copolymer particles with an average particle size rangingfrom 0.05 mm to 1.0 mm and a density ranging from 0.96 g/cm3 to 1.06g/cm3.
 9. The method according to claim 1, wherein the anti-channelingpack-off particles are polypropylene and polyvinyl chloride highmolecular polymer particles with an average particle size ranging from0.05 mm to 1.0 mm and a density ranging from 0.8 g/cm3 to 1.2 g/cm3. 10.The method according to claim 1, wherein the anti-channeling pack-offparticles are filled into the first annular space and the second annularspace until the first annular space and the second annular space aresubstantially full of the anti-channeling pack-off particles, and thefirst annular space and the second annular space are closed.
 11. Themethod according to claim 1, wherein the oil-gas well is a horizontalwell or an inclined well.
 12. The method according to claim 2, wherein adifference between a density of the particle-carrying fluid and adensity of the anti-channeling pack-off particles is within a range of±0.4 g/cm3.
 13. The method according to claim 2, wherein a differencebetween a density of the particle-carrying fluid and a density of theanti-channeling pack-off particles is within a range of ±0.2 g/cm3. 14.A sectional flow control system for an oil-gas well, comprising: a firstannular space formed between a borehole wall of the oil-gas well and aperforated pipe, wherein the perforated pipe is located inside theoil-gas well and extends along an axial direction of the oil-gas well; asecond annular space formed between the perforated pipe and a flowcontrol filter string, wherein the flow control filter string is locatedinside the perforated pipe and extends along the axial direction of theoil-gas well; and anti-channeling pack-off particles filled in the firstannular space and the second annular space such that fluid is capable offlowing in a penetration manner in the first annular space and thesecond annular space filled with the anti-channeling pack-off particles.15. The system according to claim 14, wherein the first annular spaceand the second annular space are filled by injecting particle-carryingfluid with the anti-channeling pack-off particles into the first annularspace and the second annular space.
 16. The system according to claim15, wherein the particle-carrying fluid has a density substantiallyequal to a density of the anti-channeling pack-off particles.
 17. Thesystem according to claim 15, wherein the particle-carrying fluid iswater or aqueous solution.
 18. The system according to claim 14, whereinthe anti-channeling pack-off particles are high molecular polymerparticles with an average particle size ranging from 0.05 mm to 1.0 mmand a density ranging from 0.8 g/cm3 to 1.4 g/cm3.
 19. The systemaccording to claim 14, wherein the anti-channeling pack-off particlesare high molecular polymer particles with an average particle sizeranging from 0.1 mm to 0.5 mm and a density ranging from 0.94 g/cm3 to1.06 g/cm3.
 20. The system according to claim 14, wherein theanti-channeling pack-off particles are high-density polyethyleneparticles with an average particle size ranging from 0.1 mm to 0.5 mmand a density ranging from 0.90 g/cm3 to 0.98 g/cm3.
 21. The systemaccording to claim 14, wherein the anti-channeling pack-off particlesare styrene and divinylbenzene crosslinking copolymer particles with anaverage particle size ranging from 0.05 mm to 1.0 mm and a densityranging from 0.96 g/cm3 to 1.06 g/cm3.
 22. The system according to claim14, wherein the anti-channeling pack-off particles are polypropylene andpolyvinyl chloride high molecular polymer particles with an averageparticle size ranging from 0.05 mm to 1.0 mm and a density ranging from0.8 g/cm3 to 1.2 g/cm3.
 23. The system according to claim 14, whereinthe first annular space and the second annular space are substantiallyfull of the anti-channeling pack-off particles, and are closed.
 24. Thesystem according to claim 14, wherein the oil-gas well is a horizontalwell or an inclined well.
 25. The system according to claim 16, whereina difference between the density of the particle-carrying fluid and thedensity of the anti-channeling pack-off particles is within a range of±0.4 g/cm3.
 26. The system according to claim 16, wherein a differencebetween the density of the particle-carrying fluid and the density ofthe anti-channeling pack-off particles is within a range of ±0.2 g/cm3.27. A sectional flow control method using a flow control filter stringin an oil-gas well having a perforated pipe, wherein the oil-gas wellhaving the perforated pipe comprises a borehole wall of the oil-gas welland the perforated pipe running in the oil-gas well, one end of theperforated pipe adjacent to a wellhead is fixedly connected to theborehole wall, and an annular space is formed between the perforatedpipe and the borehole wall; and wherein the sectional flow controlmethod using a flow control filter string comprises the followingsteps: 1) running the flow control filter string into the perforatedpipe via a running string, wherein the flow control filter string isprovided with a flow control filter, the flow control filter string isfixedly connected to the borehole wall, and an annular space is formedbetween the flow control filter string and the perforated pipe; 2)injecting particle-carrying fluid with the anti-channeling pack-offparticles into the annular space between the flow control filter stringand the perforated pipe, wherein the particle-carrying fluid carryingthe anti-channeling pack-off particles passes through holes in theperforated pipe and into the annular space between the perforated pipeand the borehole wall, the anti-channeling pack-off particles areaccumulated both in the annular space between the flow control filterstring and the perforated pipe and in the annular space between theperforated pipe and the borehole wall, so that the annular space betweenthe flow control filter string and the perforated pipe and the annularspace between the perforated pipe and the borehole wall are filled withand full of the anti-channeling pack-off particles; 3) closing theannular space full of the anti-channeling pack-off particles between theflow control filter string and the perforated pipe, and closing pack-offmedia in the annular space between the perforated pipe and the boreholewall; and 4) disengaging the running string which is connected to theflow control filter string, and forming a well completion structure inwhich the annular space between the flow control filter string and theperforated pipe and the annular space between the perforated pipe andthe borehole wall are filled with the anti-channeling pack-offparticles.